Encoder including moving plate, irradiator, light receiver and determination part to specify error position

Provided is an encoder capable of suppressing a decrease in detection accuracy. The encoder includes a moving plate, a light irradiator that irradiates a code pattern with light, and a light receiver. The code pattern includes a light guider and a non-light guider. A code pattern array is an array in which an error correction code for correcting an error is inserted into a position information data string that can specify a position. The light receiver includes a position detecting light receiving element that reads a position array of a code pattern and a position correcting light receiving element that outputs information for correcting an error.